Motion-picture machine with electrically operated shutter and film operator



March 11, 1952 y p DUBE 2,588,813

MOTION-PICTURE MACHINE WITH ELECTRICALLY OPERATED SHUTTER AND FILMOPERATOR 2 SHEETS-SHEET 1 Filed Oct. 14, 1948 March 11;]952 J p DUBE2,588,813

MOTION-PICTURE MACHINE WITH ELECTRICALLY OPERATED SHUTTER AND FILMOPERATOR 2 SHEETSSHEET 2 Filed Oct. 14, 1948 FIG. 5.

INVENTOR \(MQX QM QM- ATTORNEY Patented Mar. 11, 1952 MOTION-PICTUREMACHINE WITH ELEC- TRICALLY OPERATED SHUTTER AND FILM OPERATOR JosephPaul Dube, Williamstown, Mass. Application October 14, 1948, Serial No.54,512

8.0laims. (01. 8818) This invention relates to picture projectors whichare more fiexiblethan previous projectors, and which can beused forshowing individual pictures with manually controlled change from onepicture to another, or motion pictures at speeds which vary over a wide.range without flicker;

It is an object of the invention to provide an improved pictureprojector for use with film having motion picture sequences and stillpictures photographed; on. the same reel; and to provide a projector inwhich the speed of the film through the machine is independent of theshutter speed and independent of the time interval required for movingthe film: from one picture frame to the next.

One of the advantages of this invention is that motion picture film canbe used for visual education without requiring; the extensive lengthsof; film; necessary for use with conventional motion picture projectors,Pictures for, the study of machineryand production, surgery, militaryoperations, and football or other sportsmust show action at speeds much.less than the speed. of actual happenings in orderto be of maximumbenefit to the persons studying the pictures. With the projector of thisinvention, pictures taken at speeds of only- 16 frames per second can beprojected: at speeds: aslowas two frames per second,. which is only A;the. speed of the actual happening;

The amount of film required at such slow speed is only a fraction ofthat required where cameras are operated at high speeds in order toobtain slow motion from conventional motion picture projectors. Forlecture; purposes, the apparatus of this invention can be made to. showone picture,- for as longas the lecturer wants, and changes. from onepicture to another are under manual control, with the same apparatusthat can be used for projecting motion pictures.

Other objects, features, and advantages of the,

the. lines. 2-2,, 3-3 and 4-4, respectively,v f

ieu l Figiu'e- 5 is a front view, on a. reduced; scale, of, the. motion.pictureprojector shown in Fig-. ure-l.

The. motion picture projecting app ratus. i

cludes a. frame It] with a vertically extending plate I I in which thereis a film gate l2 through which a light beam passes for projecting: an.

image of a film on a screen in a manner well understood in the motionpicture art. A pressure plate l3 holds the film against. the backsurface of the plate H immediately above and below the film gate i2.There is anopening, in the pressure plate [3, corresponding, with theopening through the film gate l2. The film gate comprises the projectionstation ofthe apparatus.

The film, which is shown in dot-and-dash lines and which is indicated bythe reference character I5, passes around an upper driving sprocket I1and a lower driving sprocket 1.8. These sprockets advance the film. toand from the apparatus at a continuous and average rate, of speed. Theactual intermittent movement, of the film, one picture. frame at a time.past. the film gate, 12, is effected by claw mechanism indicatedgenerally. by the reference character 20.

The sprocket I is attached to-a shaft 22 which, turns in bearings in themain frame ID. The shaft 22 is rotated by a spur gear 23 in? mesh withan idler gear 24, on a stud shaft 25 extending from the frame is. Thisidler gear 24 is driven by another spur gear 2'1 secured to a shaft 28extending parallel with the shaft 22 and similarly J'Qurnaled' inbearings in the frame ID of the projection apparatus. The lower sprocketI8 is secured to one end of the shaft .28.

The shaft 28 is driven by a worm wheel 30 secured to the shaft 28 androtated by a worm 3| on a jack shaft 32 which is supported at oppositeends by. hearings in transverse walls of the main frame It]. A spur gear34, secured to the jack shaft 32, meshes with a driving ear 36- on ashaft 31 operated. by an electric motor, 38 through a belt 39 running onpulleys 40 that are connected. with the shaft 31 and the armature shaftof the motor 38. This motor 38 is shown with an adjustable rheostat 2for changing its speed to control the rate; of rotation of thesprockets. t7 and I8, and this motor is merely representative ofvariable speed power means. In. addition to. the sprockets i7, and 18,the motor. 38 operates cams for opening and closing switches that.control a, shutter and the. claw mech-- anism 20. There. are three suchcams including two cams 41 and 48-v secured tov a shaft 50; and. athirdcam 52 secured. to a shaft 5.4.

These cam shafts and 54 turn in. bearings. in. transverse, wallsv of themain frame l0; and; the shaft, 50 is driven from the Jack. shaft 3.2;

through spur gears 55 and 51 secured to the shafts 32 and 50,respectively. The shaft 54 is driven from the cam shaft 59 through spurgears BI and 62 secured to the shafts 5D and 54, respectively. The gearsizes are so related that the shaft 54 rotates at one-half the speed ofthe shaft 50 and the shaft 50 preferably makes one revolution for eachcycle of operation of the projection apparatus; though it will beevident that the cam shafts could make any multiple or fraction of arevolution for each cycle if the cams 41, 48 and 52 were designed forsuch operation.

Figures 3 and 4 show the switches that are operated by the cams 41, 48and 52. The cam 41 rotates between two switches 55 and 61. The

' switch 66 has an arm [9 supported by a pivot H from the main frame ofthe machine and urged toward the cam 41 by a spring 12. A cam follower13, made of electrically insulating material and connected to the arm10, rides on the peripheral surface of the cam 41. A movable switchcontact 15, carried on the upper end of the arm 19, touches a fixedswitch contact l6 whenever the cam follower '53 moves into a depression18 in the face of the cam 41. This depression it has an angular extentof the order of 40 degrees, and after making allowance for the slope atthe opposite ends of the depression, the cam 41 causes the switchcontacts 15 and 16 to touch each other during something less than 40degrees of each revolution of the cam 41.

The switch 61 is similar in construction to the switch 66 and has a camfollower 89 which touches the peripheral surface of the cam 4 at aregion which is angularly spaced from the cam follower 13 byapproximately 180 degrees. The switches 66 and 51 supply power foroperating the claw mechanism to move the film for a distance equal toone picture frame of the film.

The cam 48 operates switches 83 and 84 which are similar in constructionto the switches 56 and 61. However, the cam 48 is shaped so that 180degrees of its peripheral surface has a radius sufficient to hold theswitches 83 and 84 open, whereas the remaining angular extent of theperipheral surface of the cam is of small enough radius to permit theswitches 83 and 84 to close. The high and low parts of the cam 48 areconnected by sloping transition portions of the cam, and substantiallyone-half of each transition portion can be considered as belonging tothe part of the cam that maintains the switches 83 and 84 open, and theother one-half of each transition portion as belonging to the part ofthe cam that permits the switches 86 and 81 to close.

The shutter operating cam 52 on the shaft 54 is between two switches 86and 81. These switches are connected to an insulating disc 99 held in atransverse wall of the frame 19, and the switch assembly comprising thedisc 9! and the switches 86 and 8'! is capable of rotary movement in theframe It] about the axis of the shaft 54. Such rotary movement of theswitch assembly is restricted by a tab 92 which extends rearwardly andupwardly from the disc 99 between two adjustable abutments 93 and 94.These abutments are screws threaded through lugs on the.

back wall of the frame [0 and provided with lock nuts for holding thescrews in adjusted positions;

The adjustable abutments 93 and 94 are spaced far enough to allow anangular movement of the order of 20 degrees for the disc 90, and suchangular movement shifts the cam followers of the movable arms of theswitches 86 and 8? through the same angles as'the'disc 99 is rotated andcauses the switches 86 and 81 to open and close at different phase anglepositions of the cam 52. Since this cam 52 rotates at only one-half ofthe speed of the cams 41 and 48, a change in phase angle of 20% in theoperation of the switches 86 and 8'! corresponds with angular movementof 40 degrees for the earns 41' and 48.

The switches 83 and 84- operate the claw mechanism 29 to move the clawmechanism into and out of engagement with the sprocket openings of thefilm in a way which will be explained more fully in. connection withFigure 5. The switches 86 and 81 operate the shutter 45. The connectionsof the switches 93 and 84 with the claw mechanism can be reversed bymeans of the reversing switch 43 and must necessarily be reversedwhenever the machine is reversed. This is done automatically by havingthe switch 43 ganged with the reversing switch 4| of the motor 38, asindicated in Figure l.

The reason that it is necessary to reverse the connections of theswitches 83 and 84 (Fig. 3) is because the closing of one switch causesthe claw mechanism to engage with the film whereas the closing of theother switch causes the claw mechanism to disengage from the film. Whenthe apparatus is operating in one direction it is necessary to have theclaw mechanism engaged with the film while pulling downward, but whenthe apparatus is operating in the other direction it is necessary tohave the claw mechanism engaged with the film when the claw mechanism ismoving upward.

The reason for mounting the switches and 81 on a rotatable disc 90 is toprovide an adjustment for the timing of the shutter with respect to theoperation of the claw mechanism. When the machine is operating on onedirection, the tab 92 rests against the abutment 93, and this abutmentis adjusted to make the switch 86 swing the shutter across the film gateat the time that the claw mechanism is moving the film from one pictureframe to the next. When the machine is operating in a reverse direction,the tab 92 rests against the abutment 94, and this abutment is adjustedto synchronize the operation of the shutter with the movement of thefilm by the claw mechanism.

The tab 92 is automatically shifted from the abutment 93 to the abutment94, and vice versa, whenever the direction of movement of the machine isreversed. This is accomplished by means of a friction clutch comprisinga disc I99 (Fig. l) which is slidable on the shaft 54 and which is heldin friction contact with the back of the disc 99 by a spring I02. Thereis a key I04 in the shaft 54 and extending through the disc M9 forcausing the disc N19 to rotate as a unit with the shaft 54 while leavingthe disc free to move axially on the shaft 54.

Whenever the shaft 54 rotates, the clutch disc I90 causes the switchdisc 90 to turn in the same direction as the shaft 54 until the tab 32strikes against the abutment 93, or the corresponding abutment on theother side, depending upon the direction or rotation of the shaft.

Figure 5 shows the shutter 45 attached to the lower end of an arm H9which swings about a fulcrum pivot l l l extending from the upper partof the main frame If]. Two solenoid plungers I l3 and I [4 are connectedtogether and are connected with the arm H9 by a pin H5, this connectionhaving sufficient play to allow for the fact that the arm H9 swingsabout a center HI while the plungers H3 and H4 move in a straight line.

The plunger I I3 II4 slides in a solenoid H9. Both of these solenoidsare supported on the frame I0.

When the solenoid H8 is energized, it pulls the shutter 45 to the right,asshown in Figure 5. When the solenoid I19 is energized, it pulls theshutter 45 to the left and into the dotted line position indicated. Asthe shutter 45 swings from its full line to its dotted line position,it. passes across the film gate I2 and cuts off the light beam by whichthe film is projected. It will be apparent that the shutter operatingmotor means, comprising the solenoids H8 and H8, move the shutter at aspeed independent of the speed at which the sprocket driving motor ofthe machine is running; and the length of time that the film gate I2 iscovered depends upon the speed of operation of the shutter operatingsolenoids and the width of the shutter 45, particularly its width inexcess of the width of the film gate I2. The

speed of operation and the width of the shutter are correlated toproduce only a momentary interruption in the light, and thisinterruption is of such short duration that it is not apparent to anobserver.

Since the solenoids I I8 and H9 are energized by the switches 86 and 81,each of which is closed for a half-turn of the cam shaft 54 and a fullturn of the cam shaft 58, the shutter 45 swings across the film gatetoward the right after one movement of the film and toward the leftafter the next movement of the film. Thus the cycle of operation of theshutter 45 is twice as long as the cycle of operation of the clawmechanism that moves the film.

Figure shows also the claw mechanism 20 which comprises a claw plate I2Iwith claws I22 at one end. The other'end of the claw plate I22 is pinnedto a shaft I24 which slides up-anddown in bushings I26. These bushingsI26 are threaded through lugs I28 extending from the frame of themachine. The confronting ends 01' the bushings I26 comprise abutmentsfor limiting vertical movement of the claw plate I2I. By screwing thebushings I26 in directions to bring them closer together, the stroke ofthe claw plate I2I and shaft I24 can be changed, and the position of theclaw plate at the ends of its stroke can be varied to properly centerthe film frame in the film gate.

The claw plate I2I is moved up-and-down by an arm I3I which swings abouta fulcrum pivot I33 on the frame of the machine. The arm I3I isconnected with the claw plate I2I by a universal connection that allowsfor a limited angular movement of the claw plate I2I about the axis oftheshaft I24 so that the claws I22 can be moved into and out ofengagement with the sprocket teeth openings of the film withoutinterfering with the connection between the claw plate I 2I and itsoperating arm I3I.

Upper and lower solenoid plungers I35 and I35, respectively, areconnected together and slide vertically in solenoids I38 and I39,respectively. These solenoid plungers I35 and I36 are connected with thearm I3I by a pin connection I which is loose enough to compensate forthe angular movement of the arm I3! and the straight line movement ofthe plungers I35 .and I36.

When the solenoid I 38 is energized, it moves the claw plate I2I upwardfrom the full line position shown in Figure 5 to the dotted lineposition shown. When the solenoid I39 is energized, it pulls the clawplate I2I downward. Whether the upward or the downward movement of theclaw plate l2 brings the next frame into position for projection dependsupon whether the claws I22 are moved into engagement with the sprocketopenings of the film before the upward movement or the downward movementof the claw plate,

The shaft I24 can be turned angularly, to engage and disengage the clawsI22 and the sprocket opening of the film, by solenoids I43 and I44.These solenoids I43 and I44 operate plungers I45 and I46, respectively.A connector I48 between the plungers I45 and I 46, has a notch I50, bestshown in Figure 1, which straddles a key I52 extending downward from acollar I 53 that is rigidly pinned to the shaft I24.

Movement of the connector I48 by the solenoid plungers I45 and I45causes the opposite ends of the notch I58 to engage the key I52,depending upon the direction of movement of the connector I48, and turnthe shaft I24 angularly about its axis. When the solenoid I43 isenergized, the connector I43 is pulled to the left-hand end .01 itsstroke, and the key I52 is moved into position to rock the shaft I24 inthe direction that holds the claws I22 clear of the sprocket openings inthe film. When the solenoid I 45 is energized, the connector I48 movesthe key I52 in the direction that swings the shaft I24 into position tocause the claws I22 to engage the sprocket openings in the film.

In the operation of the machine, the solenoids H8 and H9 are energizedsuccessively to operate the shutter 45, energy to the solenoids beingsupplied by the closing of the switches 86 and 81 (Fig. 3) on the switchdisc 90. The claw plate i2I (Fig. 5) is moved up-and-down, by thesolenoids I 38 and 39 which are supplied with energy successivelythrough the switches 83 and 84 (Fig. 3). The solenoids I43 and I44 (Fig.5) which shift the claw mechanism into and out of engagement with thesprocket openings of the film are supplied with energy through theswitches 66 and 61 (Fig. 4.).

It will be apparent from the foregoing description that the shutter 45and the claw plate I2I are operated by electric motor means whichoperate independently of the motor that drives the sprockets for thefilm. Although the operation of the solenoid motor means is independentof the sprocket motor in speed of operation, the frequency of theoperation of the solenoid motor means is under control of the sprocketdriving motor because the cam shafts which operate the switches for thesolenoids are driven for the same motor that drives the film sprockets.

This independent operation of the motor means for the shutter and theclaw mechanism is important because the shutter operates just as fastwhen the sprocket motor is running slowly. or even if the sprocket motoris temporarily stopped while displaying still images and then moved atslow and irregular speed in order to bring about the operation of theshutter and claw mechanism to move the film and display the nextpicture.

The expression claw mechanism is used in the description and claims todenote apparatus that moves film intermittently for a distance equal tothe length of a film frame. Mechanical devices for this purpose,differing from that illustrated, may be equivalents in certaincombinations defined in the claims. Likewise, motor means other thansolenoids can be used in some of the combinations, and feed rollershaving no teeth may be mechanically equivalents of the :prockets forsome embodiments of the invenion.

Various changes and modifications can be made in the preferredembodiment which has been illustrated and described, and some featuresof the invention can be used alone or in different combinations withoutdeparting from the invention as defined in the claims.

What is claimed is:

1. Apparatus for projecting images from motion picture film, including aprojection station, sprockets on both sides of the projection stationfor advancing the film through the apparatus, variable speed drivingmeans connected with the sprockets, means for projecting a beam of lightthrough the film at the projection station, a plate shutter at theprojection station, a support on which the shutter oscillates back andforth across the light beam, mechanism that operates the shutter in eachdirection across the light beam at speeds independent of the speed ofthe sprockets and their driving means, and connections between thedriving means and the shutter operating mechanism for controlling thefrequency of operation of the shutter, said connections including meansthat moves the shutter in opposite directions for successive exposuresof the apparatus.

2 Picture projecting apparatus comprising a projection station, meansfor projecting a beam of light through the film at the projectionstation, a plate shutter at the projection station, a support on whichsaid plate shutter oscillates back and forth across the light beamelectric motor means that move the shutter across the light beam in onedirection to terminate one exposure period and across the light beam inthe opposite direction to terminate the next successive exposure period,electric switch means that controls the supply of power to said electricmotor means,

sprockets for advancing a film strip toward and from the projectionstation, power driving means for the sprockets including anotherelectric motor means, a device that advances the film strip one filmframe at a time past the projection station, a controller for saiddevice operated by said other electric motor means, another controllerfor adjusting the speed of said other electric motor means, andconnections between the power driving means and the electric switch foroperata ing said electric switch, means to control the supply of powerto the electric motor means to move the shutter and terminate exposureperiods in timed relation with the operation of the device that advancesthe film strip one frame at a time.

3. Picture projecting apparatus comprising a projection station, clawmechanism movable into position to engage with sprocket openings in afilm and movable in the direction of the film to bring the next pictureframe of the film into position at the projection station, solenoidmeans for moving the claw mechanism to engage the film, other solenoidmeans for moving the claw mechanism to advance the film, a switch forcontrolling the supply power to the first solenoid means, another switchfor controlling the supply of power to said other solenoid means,sprockets for advancing the film through the apparatus, driving meansfor the sprockets mechanically independent of said solenoid means, andmotion transmitting connections between the sprocket driving means andthe switches including devices for closing said switches in timedrelation with one another. 1

4. A picture projector, including in combination, a projection station,a shutter at the projection station movable transversely across a beamof light that projects images of the film at the projection station, twosolenoids connected with the shutter and operable to move the shutter inopposite directions transversely of said projection station, clawmechanism movable about a pivot into and out of engagement with sprocketopenings of the film, two solenoids connected with the claw mechanismand operable to swing the claw mechanism in opposite directions aboutits pivot, apparatus for moving the claw mechanism longitudinally of thefilm strip to advance the film and bring the next picture frame intoposition at the projection station, said apparatus including twosolenoids that move the claw mechanism in opposite directions axially ofthe pivot aboutwhich the claw mechanism swings, sprockets for advancingthe film through the projector, a continuously operating motor drivingthe sprockets, a speed control device for said motor, switches thatsupply power to the solenoids, and separate cams driven from thesprocket driving motor and having contours in such phase relation to oneanother that the cams operate the switches in timed relation and producea predetermined sequence of operation of the solenoids of the shutterand claw mechanism.

5. A motion picture projector including a projection station, sprocketsahead of and beyond the projection station for feeding a film throughthe projector, reversible motor means for operating the sprockets eitherforwardly or rearwardly, a shutter, a claw for moving the filmintermittently at the projection station, operating mechanism for theshutter and claw, and control apparatus for changing the sequence ofoperation of at least a portion of the operating mechanism for theshutter and claw when the direction of movement of the film through theprojector is reversed, said control apparatus including two switchoperators, both of which are driven from the reversible motor means andone of which includes a lost motion connection through which it isdriven from said motor means, and a friction clutch that causes the lostmotion to be taken up in different direction when the motor means isreversed, said lost motion being of sufficient extent to change thesequence in which the switch operators actuate their switches. 6. Amoving pictureprojector including sprockets for moving the film throughthe projector, a projection station, mechanism for intermittently movingthe film to bring successive film frames into position at the projectionstation, a shutter, motor means for operating the shutter, a camoperated from the film moving mechanism, said cam being rotatable aboutan axis and through a cycle, a switch assembly operated by the camduring its rotation for energizing the motor means of the shutter, meansfor reversing the direction of operation of the sprockets, and controlmeans that change the phase angle position of the switch assembly withrespect to the cam to shift the time of operation of the shutter in thecam cycle when the film driving sprockets are reversed.

7. The motion picture projector defined in claim 6 and in which theswitch operating cam is driven from the same power means that operatethe film sprockets, and in which a friction clutch is interposed betweenthe cam shaft and a portion of the switch assembly for shifting theposition of the switch assembly automatically upon the reversal the camshaft.

8. A projector for motion picture film, said projector includingsprockets for moving the film through the machine, power operatingmechanism for the sprockets, a device for reversing the operation of thepower operating mechanism, claw mechanism for moving the film, said clawmechanism including motor means for causing the claw mechanism to engageand disengage with sprocket openings in the film, other motor means forcausing the claw mechanism to move up-and-down in the direction of theintended film travel, switch means operated in timed relation with thepower operating mechanism for the sprockets for energizing the motormeans of the claw mechanism, and a reversing switch, for one of themotor means of the claw mechanism, mechanically connected with thereversing device of the sprocket operating mechanism so that thereversal of the direction of rotation of the sprockets automaticallychanges the relation of operation of the motor means of the clawmechanism and cause the claw mechanism to be in enof the direction ofrotation of gagement with the film when moving in the di- 25 rectionthat the film is advanced by the sprockets JOSEPH PAUL DUBE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,277,195 Connor et al Aug. 27,1918 1,315,224 Hill Sept. 9, 1919 1,683,303 Riddell Sept. 4, 19281,734,221 Markham Nov. 5, 1929 1,983,898 Cole Dec. 11, 1934 2,082,074Moomaw June 1, 1937 2,091,508 Howell Aug. 31, 1937 2,141,037 FranklinDec. 20, 1938 2,160,390 Pfannenstiehl May 30, 1939 2,371,836 MastersonMar. 20, 1945 2,409,834 Clapp "Oct. 22, 1946 FOREIGN PATENTS NumberCountry Date 420,302 Germany Oct. 21, 1925

